Free Ishihara Screening
Free color blind test online
Fourteen Ishihara plates, about ninety seconds, no signup. Screens for red green and blue yellow color blindness.
Hue, Not Brightness
One cone axis at a time
Each plate is a field of colored dots with a number hidden in it. The figure and the background are set apart along one cone axis only, the axis a particular deficiency cannot see along. That way the number is plain to normal color vision and vanishes for someone missing that cone.
Twelve screening plates cover the three axes four times each, and two control plates readable by everyone confirm your screen is not distorting the colors.
Generated, Not Scanned
A different test every time
The plates here are computed in LMS cone space rather than reproduced from the printed 1917 series. Figure and background are separated along the exact axis the target deficiency is missing, so the two collapse onto an identical color by construction.
Every plate is then checked against a dichromat simulation before it is shown, and any plate whose figure fails to vanish is thrown away and drawn again. Nobody else does this, and it is why the answers cannot be memorised or looked up beforehand.
The Result
Which type it points to
The score is not a pass mark. Errors are counted per axis, so a run that misses the deutan plates while reading the protan and tritan ones cleanly reports deutan. The clustering is what separates a deficiency from ordinary mistakes.
Each type has its own page explaining what it means day to day: deuteranopia, protanopia and tritanopia. Or compare all six types.
Before You Start
- Set your screen to full brightness.
- Turn off night mode and blue-light filters.
- Sit about an arm's length away, in normal indoor light.
- Wear your usual glasses or contacts, but not tinted lenses.
Answer from first impression. Studying a plate defeats it. The test measures what you see immediately, not what you can work out.
Questions People Ask
How accurate is this free color blind test?
It is a screening test, not a diagnosis. The plates are checked automatically against a dichromat simulation, so the colors themselves are correct, but your monitor, its color profile and your room lighting are not controlled. The test reliably flags whether a color vision deficiency is likely and which axis it sits on. It cannot grade severity and it does not replace an eye exam.
How long does the color blind test take?
About ninety seconds. There are fourteen plates in total: twelve screening plates covering the red green and blue yellow axes, and two control plates that confirm your screen is showing the colors correctly.
Is the test really free, and do I need to sign up?
Yes it is free, and no signup is required. There is no payment, no account and no email. The test runs entirely in your browser and your answers are never sent to a server.
Am I color blind if I fail a few plates?
Not necessarily. Everyone misreads a plate occasionally, especially in poor lighting or in a hurry. What matters is the pattern. A genuine deficiency produces errors clustered on the plates built for one cone axis, while the plates for the other two axes stay clean. The result explains which pattern your answers formed.
What is the difference between protan, deutan and tritan?
They name the cone that is affected. Protan means the red sensitive L cone, deutan the green sensitive M cone, and tritan the blue sensitive S cone. Protan and deutan both cause red green confusion, with protan also making reds look darker. Tritan causes blue yellow confusion and is far rarer.
Can I take the color blind test on my phone?
Yes, although a larger screen is better. Before you start, turn off night mode, true tone and any blue light filter, and set brightness to full. Those features shift the colors enough to affect the result, particularly on the blue yellow plates.
Why do I get different plates every time I take the test?
The plates are generated fresh in your browser for every visitor rather than reproduced from the printed 1917 Ishihara series. The dot arrangement and the hidden numbers change on every run, so the answers cannot be memorised or looked up in advance.
Is this the same as the official Ishihara test?
It uses the same principle and the same plate design classes, but it is not a scan of the printed Ishihara book. A clinical Ishihara test is administered on printed plates under daylight balanced illumination, three seconds per plate, with an eye care professional recording the answers. This is an unsupervised screening on a display of unknown calibration.
Can a color blind test be used for a job or a driving licence?
No. Occupational color vision standards for aviation, rail, maritime, the electrical trades and some emergency services are assessed with printed plates, a lantern test or an anomaloscope, administered in person. Use this to find out whether it is worth booking that appointment, not as evidence in it.
Can color blindness be cured or corrected with glasses?
Inherited color blindness cannot be cured. The cone pigment is either missing or mistuned, and no lens can replace it. Color blind glasses filter a band of the spectrum where the red and green cone responses overlap, which widens the difference between colors that used to look alike. Some people find that useful, particularly with milder anomalous forms, but it does not restore normal color vision.
What number do you see?
Press 1–5 to answer with the keyboard.